In recent years, in the field of cancer diagnosis, various cancer markers have been investigated in order to know a sign of cancer onset in an early stage, and practical applications is progressing. The cancer marker is a secretory biological factor derived from cancer cells, and increases with the progression of the cancer and appears in blood and/or urine. For example, proteins such as hormones and cytokines, and nucleic acid such as micro-RNA are known. In the early stage cancer, the amount of these cancer markers is small and difficult to detect these markers; it is the same situation when there exists the cancer marker of originally low expression level. At present, the mainstream of the high sensitive method for detecting the cancer markers is in the immunoassay method using an antibody, and the techniques such as the ELISA method and the nanoparticulate assay are known. Recently, although it is still in a study stage, as a further high sensitive immunoassay method, a digital ELISA which is capable of detecting by a single molecule has been developed (Non-Patent Literature 1). When the cancer marker in blood is detected, the amount of blood which can be collected from patient is limited; therefore, it is required to detect by capturing a trace amount of the cancer marker contained therein as much as possible. For example, if the detection is performed with 50 μl of plasma, since the cancer marker in the early stage cancer is within the concentration range from 10−16 to 10−12 M, the detection sensitivity which can determine quantitatively 3000 molecules of the target molecule present in 50 μl of the plasma is necessary. Thus, detection device with very high sensitivity which is capable of detecting the cancer markers of low concentrations is required.